1. Technical Field
The present disclosure relates to spools or bobbins for use with wire braiding machines, for example and, in particular, relates to an improved spool having a design which is useful for preventing snagging of wire upon pay-off of the wire from the spool during operation of a wire braiding machine.
2. Description of the Related Art
A schematic view of wire braiding machine 10 is shown in FIG. 1, including rotatable carousel 12 holding a plurality of spools 14 each containing a fine diameter wire 16 wound around spools 14. During operation of braiding machine 10, constituent wires 16 pay-off from their respective spools 14, with spools 14 rotating about their respective axes while being simultaneously orbited about a longitudinal axis of the machine 10. This orbiting motion is effected by carousel 12, which rotates to braid constituent wires 16 about a central mandrel wire 18 paid off from a mandrel wire spool 19. After wires 16 are braided around mandrel wire 18 to form a length of a braided wire construct 20 which may be rewound onto takeup spool 21. When ready for use in a medical device such as a catheter, for example, mandrel 18 may be withdrawn from a length of the braided constituent wires 16, such that the resulting braided wire construct forms a hollow, braided tube of wire material.
Spool 14 is shown in further detail in FIG. 2, and includes a central cylindrical barrel 22 and a pair of substantially cylindrical wire-retention flanges 24 on respective opposite sides of barrel 22. Flanges 24 define generally planar inwardly-facing end surfaces disposed perpendicular to longitudinal axis LP-LP of barrel 22. One of flanges 24 includes a plurality of ratchets 26 annularly arranged around axis LP-LP and adapted to interface with correspondingly formed ratchet structures (not shown) on carousel 12 of braiding machine 10. The spool 14 may be small in size, having an overall width WP of about 35.5 mm and a flange diameter DP of 40 mm.
One problem with the function and structure of spool 14 is schematically illustrated in FIG. 3. When wire 16 is wound onto spool 14, any winding errors or unevenness in the level of the wire winding tends to build and propagate as spool 14 is filled. For example, referring to FIG. 3, a wire build-up indicated at 28 at the right side of spool 14 near the right flange 24 is visible. Winding defects such as build-up 28 can cause snagging and/or breakage of the wire 16 upon pay-out during operation of the braiding machine 10, which in turn disrupts the continuity of braided construct 20 and necessitates shutdown of machine 10 and replacement of spool 14. These consequences, in turn, may impedes production of construct 20, generates waste and may result in suboptimal mitigation strategies by the machine operator, such as using spools 14 that are less than completely filled with wound constituent wire 16.
What is needed is an improvement over the foregoing.